This is the only episode of the 11 which does not feature Boris Karloff in a character role, and the only one to be shot in England rather than Hollywood (it was picked up by Hal Roach Studios in order to save on production costs). Karloff's introduction was filmed in Hollywood and added later.
One of 4 episodes compiled for the feature "Jack the Ripper" - the others were Summer Heat (1958), Genesis (1958), and Food on the Table (1958).